1. Field of the Invention
The invention relates to a liquid crystal alignment agent and uses thereof. Particularly, the invention relates to a liquid crystal alignment agent for forming a liquid crystal alignment film having high rubbing resistance and a liquid crystal display element containing the liquid crystal alignment film.
2. Description of the Related Art
In recent years, the development of new liquid crystal display elements has become flourishing. For example, a new liquid crystal display element is developed, wherein liquid crystals are driven by two electrodes equipped with a pectinate way on one side substrate for producing a parallel electric field on a surface of the substrate for controlling the liquid crystals. The liquid crystal display element is known as In-Plane-Switching type (IPS type) and has excellent wide view angle property. However, the IPS type liquid crystal display element has the problem of image sticking due to high ion density.
Japanese Patent Publication No. 2009-175684 discloses a liquid crystal alignment film having low ion density and a diamine compound having piperazine for forming the liquid crystal alignment film. By using the diamine compound having piperazine, the alignment film formed therefrom can improve the problem of high ion density. However, in the follow-up process, when the alignment film is under rubbing treatment by cloth, it is easy to produce debris causing low display quality so it cannot be accepted in the field.
Therefore, in order to meet the requirements of IPS type liquid crystal display elements, a liquid crystal alignment agent for forming a liquid crystal alignment film having good rubbing resistance is a target remained to be achieved.